The present invention relates to gear pumps or analogous fluid displacing machines wherein the means for conveying a fluid (e.g., oil) from the inlet to the outlet of a housing comprises the teeth of two or more mating spur gears, herringbone gears or helical gears.
The gears of a gear pump are provided with trunnions which are journalled in bearing structures mounted in or forming part of the pump housing. When the gears are rotated by a highly pressurized fluid, or when the gears are used to pressurize a fluid, the trunnions transmit to the respective bearing structures forces of substantial magnitude. Such forces are likely to damage or destroy the bearing structures and/or the gears. In many instances, the forces are large enough to effect a pronounced distortion of that surface of a bearing structure (e.g., a ring-shaped body which surrounds a trunnion with minimal clearance) which is immediately adjacent to the respective end face of the adjacent gear. This causes excessive leakage of fluid and results in pronounced wear which can bring about rapid destruction of the bearing structure, trunnion and/or gear.